Fatal road accidents are increasing because of fast driving. Nowadays, Road traffic departments are provided with different types of speed traps and cameras to place at some roads segments for the sake of detecting the speed offenders, which might help in reducing the problem. Many drivers know where those cameras and speed traps are, so they tend to reduce their speeds when approaching those cameras then, increase it back when leaving the cameras' visibility area. This research proposes a concept of an unavoidable speed offence detection system for smart cities and highways in a try of controlling the problem. The system proposes placing a set of Vehicular Ad-Hoc Network (VANET) devices on the roadside and within the vehicles to achieve side to side communication. The provided communication would be responsible for delivering real time information about the cars' instant status, including its speed, which would help in detecting the speeding offenders. By conducting this research, it is expected to produce a prototype of the system which would warn the speeding drivers at any time about their offence and to ensure a fine will be issued for every offender. In addition, the proposed system is expected to help traffic policemen in doing their job of identifying and proving that a driver has broken the road driving rules. © 2019 IEEE.